Disk cartridge

ABSTRACT

A disc cartridge is provided. The disc cartridge includes an optical disc and a main cartridge body unit rotatably housing the optical disc. A lateral surface of the main cartridge body unit as an inserting end of the main cartridge body unit into the recording and/or reproducing apparatus is a semicircular arcuate section having the center of the optical disc accommodated in the main cartridge body unit as center. The direction of insertion of the main cartridge body unit into the recording and/or reproducing apparatus may be discriminated readily to achieve smooth loading.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application claims priority to Japanese Patent ApplicationNo. 2003-281395, filed on Jul. 28, 2003, Japanese Patent Application No.2003-281391, filed on Jul. 28, 2003, and Japanese Patent Application No.2004-140491, filed on May 10, 2004, the disclosures of which in entiretyare incorporated by reference herein.

BACKGROUND OF THE INVENTION

The present invention relates to a disc cartridge having a disc-shapedrecording medium, such as an optical disc held therein.

Up to now, a disc cartridge, having a disc-shaped recording medium, suchas an optical disc, rotatably housed therein, and which is loaded on adisc recording and/or reproducing apparatus, is housed therein as adisc-shaped recording medium, has been in use extensively. This sort ofthe disc cartridge, comprising a disc-shaped recording medium, housed ina main cartridge body unit, can be loaded/unloaded for the discrecording and/or reproducing apparatus, with the disc-shaped recordingmedium in a protected state.

As this sort of the disc cartridge, such a one comprising a disc-shapedrecording medium, housed for rotation in a rectangular-shaped maincartridge body unit, is in widespread use.

Meanwhile, among the commercially available disc-shaped recordingmediums, housed in disc cartridges, there are those common in size butdifferent in the recording and/or reproducing system. The disc-shapedrecording mediums, different in the recording and/or reproducing systemmay not be recorded and/or reproduced on a common recording and/orreproducing apparatus with compatibility. The disc cartridge, housing adisc-shaped recording medium, substantially common in size, also has aouter substantially common outer shape. That is, a disc cartridgesubstantially common in outer shape but different in the recordingand/or reproducing system is now presented to the market. Among thesecommercially available disc cartridges, there are those havingdiscriminating parts for discriminating the sort of the disc-shapedrecording mediums housed therein. These discriminating parts aremechanically or electrically discernible, using a cartridgediscriminating unit provided to the recording and/or reproducingapparatus carrying the disc cartridge, but are difficult to discernreadily on visual observation.

Thus, such a disc cartridge, in which the sort of the disc-shapedrecording medium, housed therein, may readily be discerned based on theouter shape of a main cartridge body unit, has been proposed. An exampleof this disc cartridge is disclosed in the Japanese laid-Open PatentPublication H11-353845 (Patent Publication 1).

In the disc cartridge, disclosed in the Patent Publication 1, theinserting end into the recording and/or reproducing apparatus has asubstantially arcuate lateral side as an inserting end to the recordingand/or reproducing apparatus, so that the inserting direction into therecording and/or reproducing apparatus may readily be identified, whilethe mistaken insertion into the recording and/or reproducing apparatusmay readily be prevented from occurring. In addition, since the lateralside is arcuate-shaped, the disc cartridge may be smaller in size than arectangular-shaped disc cartridge.

In the disc cartridge, described in this Patent Publication 1, thelateral side of the main cartridge body unit is arcuately-shaped.However, the disc cartridge is not reduced in size in keeping with thedisc-shaped recording medium housed therein.

Moreover, the rectangular-shaped disc cartridge, so far usedextensively, may be inserted into or detached from a cartridgesupporting part of a cartridge holder provided to the recording and/orreproducing apparatus. That is, the rectangular-shaped disc cartridgemay be loaded or unloaded in stability by causing its movement along aninserting guide part provided to the recording and/or reproducingapparatus.

If, with the rectangular-shaped disc cartridge, an engagement recess,engaged by a mating engagement portion of the ejection unit provided tothe recording and/or reproducing apparatus, is provided, it is naturallyprovided in a flat surface parallel to the inserting direction.

If the inserting end of a disc cartridge into the recording and/orreproducing apparatus is arcuately-shaped, as in the disc cartridgeshown in the Patent publication 1, for reducing the size of the disccartridge in keeping with the disc-shaped recording medium accommodatedtherein, it may be difficult to provide the engagement recess, engagedby a mating engagement portion of the ejection unit provided to therecording and/or reproducing apparatus, in a flat surface extendingparallel to the inserting direction. That is, the engagement recess,which enables an ejection unit to be operated in stability during theoperation of inserting the disc cartridge into the recording and/orreproducing apparatus, it may become impossible to provide the recess inthe flat surface extending parallel to the inserting direction, as aresult of the attempt to reduce the size of the disc cartridge.

In a disc cartridge in which, for further reducing its size, an areaapproximately one-half of the inserting end into the recording and/orreproducing apparatus, it becomes impossible to provide the engagementrecess, engaged by the mating engagement portion of the ejection unit,in the flat lateral surface extending parallel to the insertingdirection.

SUMMARY OF THE INVENTION

The present invention relates to a disc cartridge, having a disc-shapedrecording medium, such as an optical disc held therein.

The present invention provides in an embodiment a disc cartridge whichmay be further reduced in size keeping with the disc housed therein.

The present invention provides in an embodiment a disc cartridge whichmay be readily smoothly loaded on a recording and/or reproducingapparatus.

The present invention provides in an embodiment a disc cartridge inwhich a part of a signal recording area of a disc housed within the maincartridge body unit may reliably be exposed to outside across the innerand outer rims of the disc.

The present invention provides in an embodiment a disc cartridge inwhich a recording and/or reproducing aperture for exposing a part of thedisc housed within the main cartridge body unit may reliably beopened/closed.

The present invention provides in an embodiment a disc cartridge inwhich a shutter unit for opening/closing the recording and/orreproducing aperture provided to the main cartridge body unit may bemoved in stability.

The present invention provides in an embodiment a disc cartridge inwhich, while the size thereof is further reduced in keeping with thedisc accommodated therein, the disc loaded on the recording and/orreproducing apparatus may reliably be ejected.

The present invention provides in an embodiment a disc cartridge inwhich engagement with the ejection unit provided to the recording and/orreproducing apparatus may be reliably achieved to enable stableejection.

The present invention provides in an embodiment a disc cartridge whichmay reliably be loaded on the recording and/or reproducing apparatus.

The present invention provides a disc cartridge comprising a disc, and amain cartridge body unit having the disc rotatably housed therein, inwhich one lateral surface of the main cartridge body unit is asubstantially semicircular arcuate section having the center of the dischoused in the main cartridge body unit as center.

With the present disc cartridge, one lateral surface of the maincartridge body unit is formed as a substantially semicircular arcuatesection having the center of the disc accommodated in the main cartridgebody unit as a center, so that at least one lateral side of the disccartridge is of a size substantially proximate to the semicircle of thedisc accommodated therein, thus achieving further size reduction of themain cartridge body unit.

the arcuate section provided to the main cartridge body unit is formedon an inserting side of the main cartridge body unit into a recordingandlor reproducing apparatus. Moreover, the back side of the maincartridge body unit opposite to the inserting end thereof formed as thearcuate section is a curved section having a curvature smaller than thatof the arcuate section.

With this disc cartridge, in which the inserting end thereof into therecording and/or reproducing apparatus is formed as a substantiallyarcuate section, the direction of insertion into the recording and/orreproducing apparatus may be discerned readily, thereby positivelyprohibiting mistaken insertion.

In addition, since the inserting end of the disc cartridge according tothe present invention is formed as a semicircular arcuate section, thedisc cartridge may be smoothly inserted over a wide angular extent intothe cartridge loading/unloading opening provided to the recording and/orreproducing apparatus.

The main cartridge body unit includes a recording and/or reproducingaperture for exposing at least a portion of the signal recording area ofthe disc to outside across the inner and outer rims of the disc. Therecording and/or reproducing aperture is formed for being opened in alateral side of the main cartridge body unit other than the lateral sideformed as the arcuate section. A shutter unit for opening/closing therecording and/or reproducing aperture is movably mounted to the maincartridge body unit. The shutter unit is moved along a lateral side ofthe main cartridge body unit other than the arcuate section of the maincartridge body unit for opening/closing the recording and/or reproducingaperture. The lateral side along which is moved the shutter unit ispreferably a side parallel to the movement direction of the shutterunit.

In this disc cartridge, the recording and/or reproducing aperture isformed facing the lateral surface of the main cartridge body unit otherthan the arcuate section thereof and hence the shutter member foropening/closing the recording and/or reproducing aperture may be movablymounted in stability to the main cartridge body unit for positivelyclosing the recording and/or reproducing aperture.

The disc cartridge of the present invention includes a disc, and a maincartridge body unit having the disc rotatably housed therein, in whichone lateral surface of the main cartridge body unit is a substantiallysemicircular arcuate section having the center of the disc housed in themain cartridge body unit as center. An engagement recess engaged by apart of an ejection unit provided to the recording and/or reproducingapparatus loaded with the disc cartridge is formed in the lateral sideof the main cartridge body unit carrying the arcuate section. A cut-outopened in an opposite direction to the inserting direction is formed ona side of the engagement recess opposite to the inserting direction intothe recording and/or reproducing apparatus.

Another engagement recess is formed in a lateral side of the maincartridge body unit carrying the engagement recess.

A recording and/or reproducing aperture for exposing at least a portionof the disc is formed in the main cartridge body unit and the recordingand/or reproducing aperture is formed for being opened in a lateralsurface of the main cartridge body unit, formed with the engagementrecess, other than the lateral side carrying the arcuate section of themain cartridge body unit. The shutter unit for opening/closing therecording and/or reproducing aperture is movably mounted to the maincartridge body unit.

When the disc cartridge of the present invention is loaded on therecording and/or reproducing apparatus, a part of the ejection unit isengaged in the engagement recess. In this case, a part of the ejectionunit may be engaged in the cut-out provided in the side of theengagement recess opposite to the inserting direction into the recordingand/or reproducing apparatus for being opened in an opposite directionto the inserting direction and hence may be engaged in thearcuately-shaped engagement recess. The part of the ejection unit may bepositively engaged with the engagement recess even in case the disccartridge is inserted at an inclination relative to the recording and/orreproducing apparatus.

Moreover, since a further engagement recess is provided in the disccartridge, in addition to the engagement recess engaged by the part ofthe ejection unit, the loading operation may be achieved by engaging theloading unit in the other engagement recess as the orientation controlmeans is engaged in the other engagement recess for orientation control.

Additional features and advantages of the present invention aredescribed in, and will be apparent from, the following DetailedDescription of the Invention and the figures.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a perspective view showing a disc cartridge according to thepresent invention, looking from an upper cartridge half side.

FIG. 2 is a perspective view showing a disc cartridge according to thepresent invention, looking from a lower cartridge half side.

FIG. 3 is a plan view showing a disc cartridge according to the presentinvention, looking from a lower cartridge half side.

FIG. 4 is a perspective view showing a shutter unit and a main cartridgebody unit carrying this shutter unit.

FIG. 5 is a perspective view showing the shutter unit and a shutter lockunit mounted on this shutter unit.

FIG. 6 is a side view showing the lateral side of the disc cartridge,carrying the shutter unit, according to the present invention.

FIG. 7 is a cross-sectional view showing the shutter unit mounted to themain cartridge body unit.

FIG. 8 is a plan view showing the shutter unit locked by the shutterlock unit.

FIG. 9 is a plan view showing the shutter unit in the unlocked state.

FIG. 10 is a plan view showing the state in which the shutter unit isbeing moved in a direction of opening an aperture for a head unit.

FIG. 11 is a plan view showing the state in which the shutter unit hasbeen moved in a direction of opening the aperture for the head unit.

FIG. 12 is a side view of the disc cartridge showing the opened state ofthe aperture for the head unit.

FIG. 13 is a plan view showing third and fourth engagement recessesprovided in the main cartridge body unit.

FIG. 14 is a perspective view showing another example of a disccartridge of the present invention, looking from the lower cartridgehalf side.

FIG. 15 is a perspective view showing an example of a disc drive deviceemploying a disc cartridge according to the present invention.

FIG. 16 is a plan view showing the state in which the disc cartridge isbeing inserted with a tilt into a cartridge insertion/ejecting openingof the disc driving unit.

FIG. 17 is a plan view showing the state in which the disc cartridge isbeing inserted with a tilt in the opposite direction into a cartridgeinsertion/ejecting opening of the disc driving unit.

FIG. 18 is a plan view showing the state in which the disc cartridge hasbeen inserted into a cartridge holder with a controlled orientation.

FIG. 19 is a plan view showing the state in which the disc cartridge hasbeen inserted into a cartridge holder to unlock the shutter unit.

FIG. 20 is a plan view showing the state in which the disc cartridge hasbeen inserted into a cartridge holder and the shutter unit has beenmoved to open the recording and/or reproducing aperture.

FIG. 21 is a plan view showing the state in which the disc cartridge hasbeen loaded into a cartridge holder to reproduce the optical disc.

FIG. 22 is a cross-sectional side view showing the state in which anoptical pickup has been moved to the outer rim side of the optical dischoused in the disc cartridge loaded on a cartridge loading section.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to a disc cartridge, having a disc-shapedrecording medium, such as an optical disc, held therein.

Referring now to the drawings, a disc cartridge according to the presentinvention is explained in detail.

A disc cartridge 1 according to the present invention houses therein anoptical disc 2, as a disc-shaped recording medium, for rotation therein,and includes a main cartridge body unit 4, made up by upper and lowercartridge halves 3, 4, abutted and bonded together, as shown in FIGS. 1and 2. The optical disc 2 is rotatably housed within this main cartridgebody unit 4.

The disc cartridge 1 according to the present invention houses thereinthe optical disc 2, on which there are recorded program data or videodata for executing e.g. a television game, and is of an extremely smallsize. The present disc cartridge 1 houses therein a small-sized opticaldisc 2 with a diameter on the order of, for example, 60 mm, and is of asize that can be held in a user's palm.

Meanwhile, the optical disc 2, housed in the present disc cartridge 1,is a replay-only disc, having information signals, such as program data,prerecorded thereon.

The upper and lower cartridge halves 3, 4, making up a main body unit 5,housing the disc cartridge 1, is molded from a synthetic resin material,and upstanding peripheral wall sections 3 a, 4 a are formed on the outerrim of the halves 3 a, 4 a, respectively. The upper and lower cartridgehalves 3, 4 are bonded together, with the peripheral wall sections 3 a,4 a abutting to each other, thereby forming a main cartridge body unit 5delimiting a disc housing section 6 therein. The upper and lowercartridge halves 3, 4 are bonded to each other to form the maincartridge body unit 5, applying a welding technique, such as anultrasonic welding technique, to welding projections formed upright onthe sides of the upper and lower cartridge halves 3, 4 facing eachother.

The main cartridge body unit 5, forming the disc cartridge 1 accordingto the present invention, has its front side, as an inserting side endof the disc cartridge 1 into the disc recording and/or reproducingapparatus, formed as an arcuate section 7, as shown in FIGS. 1 to 3.This arcuate section 7 is formed to a semicircle of the optical disc 2of a radius R1 housed within the disc housing section 6 of the maincartridge body unit 5, with the center of the disc as a center P0 of thesemicircle, as shown in FIG. 3. That is, the arcuate section 7 is formedas a semicircle commensurate with the semicircle of the optical disc 2housed within the main cartridge body unit 5.

The facing lateral sides of the main cartridge body unit 5, consecutiveto the arcuate section 7 of the main cartridge body unit 5, are formedas sides 8, 9 parallel to each other, while the back side of the maincartridge body unit 5, lying opposite to the arcuate section 7, isformed as a uniformly smoothly curved section 10. That is, the arcuatesection 7 is formed as a semicircle substantially in register with thesemicircle of the optical disc 2 housed in the main cartridge body unit5.

With the disc cartridge 1 of the present invention, the front sidethereof, as an inserting side surface, is a substantially semicirculararcuate section 7 of a curvature larger than the other side, oppositethereto, so that, when the disc cartridge is inserted in the slot-instyle via cartridge insertion/ejection opening, the direction ofinsertion into the disc recording and/or reproducing apparatus can beidentified extremely readily. In particular, with the disc cartridge 1,reduced in size so as to be held in the user's palm, the direction ofinsertion can be identified by the sensual touch feeling, thusprohibiting mistaken insertion to enable correct loading on the discrecording and/or reproducing apparatus. Moreover, with the present disccartridge 1, insertion into a slot-in type disc recording and/orreproducing apparatus may be facilitated, while positive insertion maybe assured.

Moreover, the disc cartridge 1 may be further reduced in size, ascompared to the optical disc 2, accommodated therein, by having theinserting end side formed as a substantially semicircular arcuatesection 7, and by having the back side opposite to the arcuate section 7similarly formed as a curved section 10.

At a mid part of the lower cartridge half 4, forming the lower surfaceof the main cartridge body unit 5, there is formed a circular centeropening 12 for exposing a center hole 11 of the optical disc 2 housed inthe main cartridge body unit 5 and the ambient part thereof to outside,as shown in FIGS. 2 and 3. Into this center opening 12 is intruded amating engagement portion, such as a turntable, of a disc rotatingdriving mechanism, provided to the disc recording and/or reproducingapparatus on which the disc cartridge 1 is loaded.

In the lower cartridge half 4, forming the lower surface of the maincartridge body unit 5, there is formed an aperture for the head part 13,operating as a recording/reproducing aperture. The aperture for the headpart 13 is provided to the lateral side 8 of the main cartridge bodyunit 5, and is formed as a rectangular aperture sized so as to be largeenough to permit a signal recording region of the optical disc 2accommodated in the main cartridge body unit 5 to be exposed to outsideacross the inner and outer rims of the disc. That is, the aperture forthe head part 13 is formed for being opened in the linear flat lateralside 8 different from the front side of the main cartridge body unit 5carrying the arcuate section 7.

A shutter unit 15 for opening/closing the aperture for the head part 13is movably mounted to the disc cartridge 1. The shutter unit 15 includesa flat-plate-shaped shutter member 16 of a rectangular shape largeenough to close the aperture for the head part 13 and a retention part17 of a U-shaped cross-section formed at the proximal side of theshutter member 16.

The shutter member 15 is formed by punching and warping a thin metalsheet or by shaping a synthetic resin material.

The shutter unit 15 is designed so that the upper cartridge half 3 ofthe cartridge body unit 5 is carried by the retention part 17 and iscarried for movement in the directions indicated by arrows A and B foropening/closing the aperture for the head part 13. That is, the shutterunit 15 is mounted for movement on the main cartridge body unit 5 by aslide guide 18 being carried by the retention part 17, as shown in FIG.4. The slide guide 18 is formed by a portion of an upstanding peripheralwall section 3 a of the upper cartridge half 3.

Referring to FIGS. 4 and 5, the retention part 17, provided to theshutter unit 15, is formed with a connecting piece 21 upstanding fromthe proximal end of the shutter unit 16, and a first engagement piece22, bent towards the shutter unit 16, is provided to the distal end ofthe connecting piece 21. On both sides of the connecting piece 21, asecond engagement piece 23, bent in an L-shape, is formed at a lowerposition than the first engagement piece 22. Meanwhile, the secondengagement piece 23 is bent in an L-shape so that its distal end isprotruded towards the first engagement piece 22.

The shutter unit 15 is arranged on the main cartridge body unit 5 sothat the shutter member 16 is extended over the aperture for the headpart 13, as shown in FIG. 2. At this time, the shutter unit 15 holds theretention part 17 in a clinching fashion by the first and secondengagement pieces 22, 23, by the first engagement piece 22 of theretention part 17 engaging in an engagement groove 24 formed in thelateral side of the slide guide 18 and by the L-shaped second engagementpiece 23 engaging with the distal end of the slide guide 18, as shown inFIGS. 6 and 7. The shutter unit 15, carried in this manner, is moved inthe directions indicated by arrows A and B for opening/closing theaperture for the head part 13, by being guided by the retention part 17.

The area of the lower cartridge half 4, traversed by the shutter member16, is formed with a recessed shutter slide part 19. This shutter slidepart 19 is formed to a depth such that the shutter member 16 is notprotruded from the surface of the main cartridge body unit 5.

In the disc cartridge 1 of the present invention, a cut-out 25 is formedin a region of the upstanding peripheral wall section 4 a of the lowercartridge half 4 facing the aperture for the head part 13, as shown inFIGS. 4 and 7. That is, the aperture for the head part 13 serves forexposing an area of the main cartridge body unit 5 extending from theinner rim up to the outer rim of the main cartridge body unit 5.

At least the part of the slide guide 18 of the upper cartridge half 3facing the aperture for the head part 13 is of a height H₁ notprotruding from the lower surface 2 a of the optical disc 2, facing thelower cartridge half 4, when the optical disc 2 loaded in the disccartridge 1 in position as to the height on the cartridge loadingsection in the disc recording and/or reproducing apparatus is loaded onthe turntable, as shown in FIG. 7.

With the above-described disc cartridge 1, when the shutter unit 15 ismoved to open the aperture for the head part 13, the optical pickup, asa head part for reading out the information signals recorded on theoptical disc 2, may be located in its entirety within the main cartridgebody unit 5. In addition, when the optical pickup has been moved to aposition scanning the outer rim of the optical disc 2, the opticalblocks other than an objective lens, converging the light beam, used forscanning the signal recording area of the optical disc 2, may be locatedoutside the main cartridge body unit 5, as the objective lens is locatedwithin the main cartridge body unit 5, as will be explainedsubsequently.

Hence, with the disc cartridge 1 of the present invention, the opticalpickup may be located across the inner part and an outer part of themain cartridge body unit 5, as the optical pickup is proximate to theoptical disc 2. Thus, the signal recording area may be formed up to theouter rim of the optical disc 2, thereby increasing the recordingcapacity of the optical disc 2. Moreover, since the optical pickup maybe proximate to the optical disc 2, the numerical aperture NA of theobjective lens may be larger, while the spot of the light beam condensedon the optical disc 2 may be smaller, thereby increasing the recordingdensity of the information signals recorded on the optical disc 2. Sincethe recording density may be improved with increase in the recordingcapacity, the optical disc in need of a preset recording capacity may bereduced in diameter. Since the optical disc 2 may be scanned as theoptical pickup is positioned for movement across the inner and outerparts of the main cartridge body unit 5, the main cartridge body unit 5may be reduced in size, whilst the disc recording and/or reproducingapparatus, employing the disc cartridge 1, may also be reduced in size.

In the disc cartridge 1, according to the present invention, the shutterunit 15, opening/closing the aperture for the head part 13, is mountedfor movement along the flat lateral surface 8 of the main cartridge bodyunit 5, as shown in FIGS. 1 and 2. Thus, the shutter unit 15 is movedlinearly with the retention part contacting with the planar lateralsurface 8, and hence may be moved in stability.

With the disc cartridge 1 according to the present invention, theshutter unit 15, adapted for opening/closing the aperture for the headpart 13, is mounted for movement with the retention part contacting withthe planar lateral surface 8, as shown in FIGS. 1 and 2. Since theretention part 17 is moved linearly along the flat lateral side 18, theshutter unit 15 may be moved in stability.

Since the aperture for the head part 13 is formed at a location facingthe flat lateral side 8 of the main cartridge body unit 5, part of thelower cartridge half 4 carrying the cut-out 25 is also formed as alinear surface. Thus, with the aperture for the head part 13, formedwith the cut-out 25 and opened on the side of the lateral surface 8 ofthe main cartridge body unit 5 facing to outside, it is possible toclose the rectangular-shaped shutter member 15, carrying a linearU-shaped retention part 17, more reliably.

The disc cartridge 1 according to the present invention is provided witha lock unit 27 for prohibiting the movement of the shutter unit 15 whenthe shutter unit 15 has been moved to a position closing the aperturefor the head part 13. The lock unit 27 of the shutter unit 15 includes alock lever 28, mounted for rotation to the shutter unit 15, and anengagement part 29 on the main cartridge body unit 5, engaged by thislock lever 28, as shown in FIGS. 5 and 8.

The lock lever 28, forming a lock member of the lock unit 27, is formedas an elongated plate-shaped member, including an upstanding thrust part30, extending along a lateral side edge thereof, and an upstandingengagement piece 31 on the opposite side for engagement by theengagement part 29, as shown in FIGS. 5 and 8. The lock lever 28 isrotationally mounted on a lock lever mounting piece 32 provided to theshutter unit 15. The lock lever mounting piece 32 is formed forprotruding laterally of the shutter member 16 from the upper edge of theconnecting piece 21 forming the slide guide 18.

The lock lever 28 is rotatably mounted about a pivot 35 as the center ofrotation, so that the thrust part 30 at one end thereof faces arectangular window 33 formed at a mid portion of the connecting piece21, as shown in FIGS. 1, 6 and 8. At this time, the engagement piece 31,provided to the opposite side of the lock lever 28, is protrudedlaterally of the shutter member 16 for extending along the lock levermounting piece 32.

A window 33 formed in the connecting piece 21 of the shutter unit 15 isengaged by a shutter unit movement inhibiting spring, provided forinhibiting movement of the shutter unit 15 to the disc recording and/orreproducing apparatus, to which the disc cartridge 1 is mounted.

The lock lever 28, carried by the shutter unit 15, is rotationallybiased by a rotational force energizing spring 37, coiled about thepivot 35, in a direction shown by an arrow C in FIG. 8 for protrudingthe thrust part 30 from the window 33. The rotational force energizingspring 37 is formed by a torsion coil spring, and has one arm section 37a retained by the thrust part 30, while having the other arm section 37b retained by the inner surface of the connecting piece 21 of theshutter unit 15, for rotationally biasing the lock lever 28 in thedirection indicated by arrow C in FIG. 8.

The rotational position of the lock lever 28 by the rotational forceenergizing spring 37 is determined by abutment of the side of the locklever 28 carrying the thrust part 30 against the connecting piece 21.

The shutter unit 15, carrying the lock lever 28 as described above, ismounted for movement to the main cartridge body unit 5, by having theretention part 17 carried by the upper cartridge half 3, as describedabove.

When the shutter unit 15 is at a position of closing the aperture forthe head part 13, as shown in FIGS. 6 and 8, the lock lever 28 isrotated in the direction of arrow C in FIG. 8, under the biasing forceof the rotational force energizing spring 37, for intruding the thrustpart 30 into the window 33 formed in the connecting piece 21. At thistime, the lock lever 28 inhibits movement of the shutter unit 15, by theengagement piece 31 thereof engaging with a mating engaging part 29,provided to the main cartridge body unit 5, while retaining the aperturefor the head part 13 in a state of closure by the shutter unit 16.

The mating engaging part 29 of the main cartridge body unit 5 isprovided to an area of the inner surface of the lower cartridge half 4,outside the area of the disc housing section 6, which may be engaged bythe engagement piece 31 of the lock lever 28 when the shutter unit 15 isin the closure position. The mating engaging part 29 is formed as onewith the lower cartridge half 4. The mating engaging part 29 is formedwith an engagement recess 29 a opened on one side. In this engagementrecess 29 a is intruded the engagement piece 31 provided to the locklever 28.

When the disc cartridge 1 is introduced into the disc recording and/orreproducing apparatus, the lock lever 28, which has locked the shutterunit 15 in the closure position, is rotated in the direction indicatedby arrow D in FIG. 8, against the bias of the rotational forceenergizing spring 37, by the thrust part 30 being thrust by the shutterunit movement inhibiting spring intruded into engagement with the window33 formed in the connecting piece 21. When the lock lever 28 is rotatedin the direction of the arrow D in FIG. 8, the engagement piece 31 isdisengaged from the engagement recess 29 a of the mating engaging part29, as shown in FIG. 9, for detaching the engagement piece 31 from theengagement recess 29 a of the mating engaging part 29, thereby unlockingthe shutter unit 15. The shutter unit 15 may now be movable along thedirection of the arrow A in FIG. 2, that is, in a direction of openingthe aperture for the head part 13.

Meanwhile, the opening/closure of the aperture for the head part 13 isby relative movement between the main cartridge body unit 5 and theshutter unit 15. The opening/closure of the aperture for the head part13 will be explained in detail subsequently.

With the above-described lock unit 27 for the shutter unit 15, in whichthe lock lever 28, locking the shutter unit 15 in the closure position,is mounted to the shutter unit 15, movable with respect to the maincartridge body unit 5, the lock lever may be moved in unison with theshutter unit 15 to follow up with the opening/closure of the aperturefor the head part 13. As a result, the lock lever 28 may be placed suchthat, when the shutter unit 15 is in the position of closing theaperture for the head part 13, at least the thrust part 30 overlies theaperture for the head part 13, thus enabling the size of the disccartridge 1 to be reduced. That is, it should be necessary to providethe space, in which to arrange the lock lever 28 in its entirety, to themain cartridge body unit 5, in case the lock lever 28 is provided to themain cartridge body unit 5. This necessity may be eliminated with thedisc cartridge 1 of the present invention, such that it is onlysufficient to provide solely the mating engaging part 29, engaged by aportion of the lock lever 28, with the consequence that the maincartridge body unit 5 may further be reduced in size.

The disc cartridge 1, according to the present invention, may further beprovided with a shutter opening/closure unit 38 which implementsreliable movement of the shutter unit 15 opening/closing the aperturefor the head part 13 and which reliably holds the shutter unit 15 in theposition of opening or closing the aperture for the head part 13.

This shutter opening/closure unit 38 is formed using a bi-directionalenergizing unit for selectively energizing the shutter unit 15 intomovement in two directions, viz. in a direction of opening the aperturefor the head part 13 and in a direction of closing the aperture for thehead part. Specifically, the bi-directional energizing unit is formed bya torsion coil spring 39, as shown in FIG. 8. This torsion coil spring39, mounted between the shutter unit 15 and the main cartridge body unit5, is arranged at a location towards which the shutter unit 15 is movedin the direction of opening the aperture for the head part 13, as shownin FIG. 8. Specifically, the torsion coil spring 39 is mounted by havingthe distal end of an arm section 39 a engaged in an engagement opening40 formed in the distal end of the lock lever mounting piece 32 and byhaving a ring 41 at the distal end of the other arm section 39 b engagedby a support pin 42 protuberantly formed on the inner surface of themain cartridge body unit 5.

When the torsion coil spring 39 is at the position of closing theaperture for the head part 13, the torsion coil spring 39 biases theshutter unit 15 in the direction indicated by the arrow B in FIG. 8 forretaining the state of closing the aperture for the head part 13. Whenthe disc cartridge 1 is loaded on the disc recording and/or reproducingapparatus, and the shutter unit 15, released from the locked state bythe lock unit 27 for the shutter unit, is moved relative to the maincartridge body unit 5 in the direction of the arrow A in FIG. 8 foropening the aperture for the head part 13, a coil part 39 c, formedcentrally of the spring in an unfixed state, is moved in the directionof arrow A, along which is moved the shutter unit 15. When the coil part39 c is further moved along the direction of the arrow A and is movedbeyond the location of a support pin 42 along the direction of movementof the shutter unit 15, as shown in FIG. 10, the biasing direction isreversed. On reversion of the biasing direction, the torsion coil spring39 biases the shutter unit 15 into movement along the arrow A in FIG.10. Thus, the shutter unit 15 is moved in a direction of opening theaperture for the head part 13, to retain the aperture for the head part13 in the opened position, as shown in FIGS. 11 and 12

When the disc cartridge 1, in a state in which the shutter unit 15retains the aperture for the head part 13 in the opened position, istaken out from the disc recording and/or reproducing apparatus, by wayof performing the operation for ejection, the shutter unit 15 is movedalong the direction of arrow B in FIG. 10, relative to the maincartridge body unit 5, with the center coil part 39 c being similarlymoved along the direction of arrow B. When the shutter unit 15 isfurther moved along the direction of arrow B, such that it surpasses thelocation of the support pin 42 along the direction of movement of theshutter unit 15, the biasing direction is reversed. On reversion of thebiasing direction, the torsion coil spring 39 biases the shutter unit 15into movement along the arrow B in FIG. 9, such that the shutter unit 15is moved in the direction of closing the aperture for the head part 13,thereby retaining the aperture for the head part in the closed state.

The shutter unit 15, biased by the torsion coil spring 39, forming thebi-directional energizing unit, is carried in the position of closingthe aperture for the head part 13 and in the position of opening theaperture for the head part 13, under the biasing force of the torsioncoil spring 39, and hence may be maintained reliably in the position ofclosing or opening the aperture for the head part 13.

In the disc cartridge 1, according to the present invention, providednot only with the lock unit 27 for the shutter unit, locking the shutterunit 15 in the closed position, but also with the shutteropening/closure unit 38, having the bi-directional energizing unit forselectively biasing the shutter unit 15 in the two directions, theshutter unit 15 may be reliably retained in the position of closing theaperture for the head part 13, while the reliable opening/closureoperation for the aperture for the head part 13 may be achieved.

For reliably closing the aperture for the head part 13, it is onlysufficient to provide the lock unit 27 for the shutter unit. Forimplementing a stable opening/closure movement of the shutter unit 15,maintaining the closed state of the aperture for the head part 13, andfor reliably maintaining the opened state of the aperture for the headpart 13, it is possible to provide only the shutter opening/closure unit38 having the bi-directional energizing unit.

In the disc cartridge 1, according to the present invention, the lateralsurface 8 of the main cartridge body unit 5, carrying the shutter unit15, is formed with a guide groove 49, into which is intruded a shutterunit releasing piece, provided to the disc recording and/or reproducingapparatus, as shown in FIGS. 1, 6 and 12.

In the lower surface of the main cartridge body unit 5, on both sides ofthe back surface, forming the curved section 10, there are formed firstand second positioning holes 43, 44, engaged by positioning pins,provided to the disc recording and/or reproducing apparatus, as shown inFIGS. 2 and 3. Meanwhile, the second positioning hole 44 is formed as anelongated hole, having the width-wise direction, lying at right anglesto the direction of movement of the shutter unit 15, as a long radius.

On both sides of the arcuate section 7 of the disc cartridge 1,operating as an inserting end of the disc cartridge 1 into the recordingand/or reproducing apparatus, there are provided first and secondengagement recesses 45, 46 engaged by a portion of a cartridge loadingunit provided to the recording and/or reproducing apparatus or a portionof a loading controlling member provided to the recording and/orreproducing apparatus, as shown in FIGS. 1 and 2.

In a location proximate to the opposite lateral side 9 of the arcuatesection 7, there is provided a third engagement recess 47 engaged by aportion of an ejection unit provided to the recording and/or reproducingapparatus, as shown in FIG. 3. Moreover, in a flat lateral side 9 of themain cartridge body unit 5, formed with the engagement recess 47 forejection of the main cartridge body unit 5, there is formed a fourthengagement recess 48.

The third engagement recess 47 is formed so that one lateral sidethereof is proximate to a center P3 along the longitudinal direction ofan area of the lateral side of the arcuate section 7 of the maincartridge body unit 5, as shown in FIG. 4. The longitudinal direction iscoincident with the inserting direction of the main cartridge body unit5 into the recording and/or reproducing apparatus. That is, the thirdengagement recess 47 is formed towards the inserting direction from acenter P3 into the recording and/or reproducing apparatus.

In the surface of the third engagement recess 47 opposite to theinserting direction E into the recording and/or reproducing apparatus,there is formed a cut-out 49 formed in a direction opposite to theinserting direction, as shown in FIG. 13. This cut-out is formed todelimit a lug 49 a at a location of the third engagement recess 47opposite to the direction of insertion E into the recording and/orreproducing apparatus for protruding in the inserting direction.

The fourth engagement recess 48 is formed as a rectangular-shaped recessopened in the lateral surface 9 of the main cartridge body unit 5.

With the disc cartridge 1 of the present invention, in which there isprovided the cut-out 49 a in the surface of the third engagement recess47 inclined in the opposite direction to the inserting direction intothe recording and/or reproducing apparatus, the ejection lever mayreliably be engaged with the disc cartridge 1 by having the distal endof the ejection lever, as a part of the ejection unit provided to therecording and/or reproducing apparatus, engaged with the surface formedwith the cut-out 49. For example, even if the disc cartridge 1 isinserted with a tilt into the recording and/or reproducing apparatus,and the ejection lever is intruded obliquely into the engagement recess47, the inclined cut-out 49 a is able to take up the tilt to achievereliable engagement. Since the present disc cartridge 1 may reliably beengaged with the ejection unit, the bias force for ejecting the disccartridge 1 may be stored in the ejection unit as a result of theinsertion into the recording and/or reproducing apparatus. The result isthat, by employing the disc cartridge 1 according to the presentinvention, a recording and/or reproducing apparatus, enabling reliableejection, may be achieved.

In particular, with the present disc cartridge 1 of the presentinvention, in which the engagement recess 47 is provided in the arcuatesection 7 and yet the reliable engagement with the ejection unit of therecording and/or reproducing apparatus may be achieved, the recordingand/or reproducing apparatus may be reduced in size without constraintas to the mounting position of the ejection unit.

Moreover, with the present disc cartridge 1 of the present invention, inwhich the fourth engagement recess 48 as a further engagement recess isprovided in addition to the third engagement recess 47 engaged by a partof the ejection unit, the loading operation to the recording and/orreproducing apparatus may be achieved by exploiting only the lateralsurface 9, by engaging the loading unit with the fourth engagementrecess 48, as a part of the orientation control unit for controlling theinserting direction of the disc cartridge 1 is engaged e.g. with thethird engagement recess 47 to control the orientation of insertion intothe recording and/or reproducing apparatus. Since the lateral side 8 ofthe disc cartridge 1, carrying the shutter unit 15, is carried by ashutter releasing means, adapted for releasing the shutter unit 15, theloading operation becomes possible by exploiting only one lateral side 9of the disc cartridge 1.

Since the loading unit may be provided only on one side of the disccartridge 1, according to the present invention, the recording and/orreproducing apparatus provided with the loading unit may readily bereduced in size.

In the lateral sides 8, 9 or the bottom surface of the cartridge mainbody unit 5, a discriminating opening or a discriminating recess foridentifying the sort of the optical disc 2 is provided as necessary.

The disc cartridge 1, according to the present invention, is insertedinto the recording and/or reproducing apparatus, with the semi-circulararcuate section 7 as an inserting end, so that it is loaded on orunloaded from the apparatus as the user grips the back side curvedsection 10, opposite to the arcuate section 7. In addition to theinserting end of the disc cartridge 1 being formed as the semicirculararcuate section 7, the disc cartridge 1 is formed to an extremely smallsize. Thus, a roughed surface for anti-slip 48 may be provided on theback surface of the lower cartridge half 4, for assuring reliablegripping by hand or finger during loading/unloading on or from therecording and/or reproducing apparatus, as shown in FIG. 14. Thisroughed surface 48 is provided on the back surface formed as the curvedsection 10 of the lower cartridge half 4.

The roughed surface 48 may also be provided to the upper cartridge half3. In this case, the roughed surface 48 is provided facing the roughedsurface 48 of the lower cartridge half 4.

An embodiment of the disc recording and/or reproducing apparatus,employing the disc cartridge 1, according to the present invention, ishereinafter explained.

In the disc cartridge 1, according to the present invention, there ishoused the optical disc 2, having recorded thereon the program data orvideo data needed for executing e.g. a TV game. The disc recordingand/or reproducing apparatus, employing the disc cartridge 1 of thepresent invention, housing this sort of the optical disc 2, is made upby a main body unit of the apparatus 51, carrying the disc cartridge 1,and having enclosed therein a disc driving unit for reproducing at leastdata recorded on the optical disc, and by a display 52 for demonstratingimage data or text data reproduced from the optical disc 2, as shown inFIG. 15.

Within the main body unit of the apparatus 51 of a disc driving device50, having enclosed therein the disc driving unit, shown in FIG. 15,there is provided a cartridge loading unit, not shown, including acartridge holder for loading the disc cartridge 1 thereon. In the frontsurface, forming one of the lateral sides of the main body unit of theapparatus 51, there is formed a cartridge inserting/ejecting opening 53for inserting the disc cartridge 1 into a cartridge holder and forejecting the disc cartridge 1 loaded in the cartridge holder. Thecartridge inserting/ejecting opening 53 is formed as an opening justlarge enough to permit insertion/removal of the disc cartridge 1, andhas a width W2 and a height H2 slightly larger than the width W1 and athickness D1, respectively, of the disc cartridge 1 inserted therein.Within the main body unit of the apparatus 51, there is arranged acartridge holder 54 facing the cartridge inserting/ejecting opening 53.

On one side of the front surface of the main body unit of the apparatus51, there is mounted an ejection button 55 for ejecting the disccartridge 1 held by the cartridge holder 54.

On one side of the upper surface of the main body unit of the apparatus51, there are provided actuating buttons 56, 57 of a control switch,used for carrying out e.g. a TV game. On the other side thereof, acontrol key 58 for scrolling the image demonstrated on the display 52.There is also provided a loudspeaker 59 for radiating audio signalsreproduced from the optical disc 2.

Although not shown, a control bobbin for e.g. a reproducing button, forcontrolling the disc driving unit, and an actuating button for a powersupply switch, are provided to the main body unit of the apparatus 51.

The display 52 is provided on the back side, opposite to the front side,carrying the cartridge inserting/ejecting opening 53 of the main bodyunit of the apparatus 51, for swinging relative to the main body unit ofthe apparatus 51 via a hinge unit 60. The display 52 may be swungtowards the main body unit of the apparatus 51 so as to be superposed onthe upper surface thereof. The display 52 is formed by a liquid crystaldisplay panel.

The state in which the disc cartridge 1 according to the presentinvention is loaded on the disc driving unit 50, constructed asdescribed above, is hereinafter explained.

For loading the disc cartridge 1 on the disc driving device 50, the disccartridge 1 is inserted via the cartridge inserting/ejecting opening 53into the main body unit of the apparatus 51, with the arcuate section 7as the inserting side, so as to be held on the cartridge holder 54, asshown in FIG. 15.

Meanwhile, with the disc cartridge 1 according to the present invention,the inserting end thereof via the cartridge inserting/ejecting opening53 is formed as the approximately semicircular arcuate section 7, sothat, even when the disc cartridge 1 is inserted with a centerline P2along the width-wise direction of the disc cartridge significantlyinclined with respect to the centerline P1 along the width-wisedirection of the cartridge inserting/ejecting opening 53, the disccartridge can be smoothly inserted into the cartridge inserting/ejectingopening 53 and reliably held by the cartridge holder 54.

That is, the disc cartridge 1, having the inserting end formed as theapproximately semicircular arcuate section 7, may be inserted into themain body unit of the apparatus 51 at the approximately semicirculararcuate section 7, even in case the disc cartridge 1 is inserted via thecartridge inserting/ejecting opening 53 with the width-wise centerlineP2 inclined by an angle up to approximately 45° towards left or right ofthe width-wise centerline P1 of the cartridge inserting/ejecting opening53, as shown in FIG. 16 or 17. At this time, the disc cartridge 1 may becorrected in its orientation by rotating it in a direction causing thecoincidence of the centerlines P1 and P2, in the course of the insertionthereof through the cartridge inserting/ejecting opening 53, with theportion of the arcuate section 7, abutting against one of the lateralsides of the cartridge inserting/ejecting opening 53, as the center ofrotation, as shown in FIG. 18. Thus, the disc cartridge 1, according tothe present invention, may reliably be inserted into the cartridgeholder 54, even in case the inserting direction thereof through thecartridge inserting/ejecting opening 53 is inclined significantly.

The disc cartridge 1, inserted into the cartridge holder 54, is furtherintroduced into the cartridge holder 54, whereby the shutter unit 15 ismoved relative to the main body unit of the apparatus 51 to open theaperture for the head part 13. That is, when the disc cartridge 1 hasbeen introduced halfway in the cartridge holder 54, as shown in FIG. 19,a portion of a shutter unit movement inhibit spring 62, formed bysegmenting a part of the sidewall section of an L-shaped cartridgeretention part 61 in one lateral side of the cartridge holder 54, isintruded into the window 33 formed in the connecting piece 21 of theshutter unit 15, thereby thrusting the thrust part 30 to cause rotationof the lock lever 28 in the direction indicated by arrow D in FIG. 9, asdescribed previously. When rotated in the direction indicated by arrow Din FIG. 9, the lock lever 28 is disengaged from the mating engaging part29 of the engagement piece 31 to release the lock of the shutter unit 15with respect to the main cartridge body unit 5. When unlocked from themain cartridge body unit 5, the shutter unit 15 is movable relative tothe main cartridge body unit 5.

The cartridge holder 54, on which is loaded the disc cartridge 1according to the present invention, is further provided with a shutterreleasing piece 63. This shutter releasing piece 63 is intruded into aguide groove 49, formed in the lateral surface 8 of the main cartridgebody unit 5, until it abuts against the lateral side of the shutter unit15.

When inserted into the inside of the cartridge holder 54, untilunlocking of the shutter unit 15, the shutter releasing piece 63 abutsagainst the lateral side of the shutter unit 15, to inhibit the movementof the shutter unit 15 relative to the main cartridge body unit 5, asshown in FIG. 19. When the disc cartridge 1 is further intruded from theposition shown in FIG. 19 towards the inner part of the cartridge holder54, in the direction indicated by arrow E, the main cartridge body unit5 is moved along the direction as indicated by arrow E, thereby openingthe aperture for the head part 13, as shown in FIG. 20.

If, as the movement of the shutter unit 15 is inhibited, the disccartridge 1 is moved in the direction indicated by arrow E in FIG. 19,with the main cartridge body unit 5 then opening the aperture for thehead part 13, the torsion coil spring 39, forming the shutteropening/closure unit 38, is biased, as described above with reference toFIGS. 9 and 10. When the main cartridge body unit 5 is moved in thedirection indicated by arrow E in FIG. 19, such that the coil part 39 csurpasses the location of the support pin 42, lying along the directionof movement of the shutter unit 15, thus biasing the torsion coil spring39, the biasing direction of the torsion coil spring 39 is reversed. Theshutter unit 15 is then moved in the direction of arrow F in FIG. 18,opposite to the direction of movement of the main cartridge body unit 5,thus opening the aperture for the head part 13, as shown in FIGS. 11, 12and 18. At this time, the shutter unit 15 is biased by the torsion coilspring 39 for opening the aperture for the head part 13, thus reliablyretaining the aperture for the head part 13 in the opened state.

The disc cartridge 1, inserted into the cartridge holder 54, with theaperture for the head part 13 opened by the above-described operation,is loaded in position on the cartridge loading section, provided in thedisc driving device 50. At this time, the optical disc 2 is loaded inposition in a disc driving unit. This disc driving unit is then actuatedto reproduce the program data recorded on the optical disc 2 to run theprogram.

For ejecting the disc cartridge 1, loaded on the disc driving device 50,after reproducing the optical disc 2, an ejection button 55 is pressed.On pressing the ejection button 55, the disc cartridge 1, loaded on thecartridge loading section, is ejected. After the ejection operation iscarried out, the shutter unit 15 is moved relative to the main cartridgebody unit 5 to revert to the initial position of closing the aperturefor the head part 13 to lock the shutter unit 15 in this position ofclosing the aperture for the head part 13, by the reverse of theoperation, described above. By this operation of restoring the shutterunit 15 to the closure position, the disc cartridge is ejected via thecartridge loading/unloading opening 53, so that the ejection of the disccartridge 1, loaded on the disc driving device 50, comes to a close.

Meanwhile, the cartridge loading section 67 is mounted on a base 69carrying a disc rotating driving unit 65 and an optical pickup 68 forreproducing the data recorded on the optical disc 2. The cartridgeloading section 67 is provided with a positioning pin 70 for positioningthe disc cartridge 1 in the planar direction and a positioning lug, notshown, for positioning the disc cartridge 1 in the height-wisedirection. The disc cartridge 1 is loaded on the cartridge loadingsection 67, as it is positioned in the planar and height-wisedirections, by the positioning pin 70 engaging in each of the first andsecond positioning holes 43, 44 and by the lower surface being supportedby the height positioning lug.

With the disc cartridge 1 of the present invention, the portion facingthe aperture for the head part 13 of the upstanding peripheral wallsection 4 a of the lower cartridge half 4 is formed with the cut-out 25and thereby opened.

At least the portion facing the aperture for the head part 13 of theslide guide 18 carrying the shutter unit 15 provided to the uppercartridge half 3 is of a height H1 not protruding from the lower surface2 a of the optical disc 2 facing the lower cartridge half 4, as shown inFIG. 7, when the optical disc 2 in the disc cartridge 1, loaded inposition in the height-wise direction on the cartridge loading section67 has been loaded in position on the turntable 6.

The disc cartridge 1, constructed as described above, is able not onlyto locate an entire optical pickup 68, as a head part for reading outinformation signals, recorded on the optical disc, within the maincartridge body unit 5, as shown in FIG. 21, when the shutter unit 15 hasbeen moved to open the aperture for the head part 13, but also to locatethe components of the optical block 72, other than an objective lens 71,condensing the light beam, scanning the signal recording area of theoptical disc 2, outwardly of the main cartridge body unit 5, as theobjective lens 71 is located within the main cartridge body unit 5, asshown in FIG. 22, when the optical pickup 68 has been moved to aposition scanning the outer rim of the optical disc 2.

As a result, with the disc cartridge 1, according to the presentinvention, the optical pickup 68 may be located at an optional positionacross the inner and outer rims of the main cartridge body unit 5, asthe optical pickup is kept in proximity to the optical disc 2, and hencethe signal recording area may be provided up to the outer rim of theoptical disc 2, thus increasing the recording capacity of the opticaldisc 2. Moreover, since the optical pickup 68 may be located inproximity to the optical disc 2, the numerical aperture NA of theobjective lens 71 may be increased, and hence the beam spot of the lightbeam condensed on the signal recording area of the optical disc 2 may bereduced, thereby improving the recording density of the informationsignals recorded on the optical disc 2. In addition, since the recordingdensity may be improved with increase in the recording capacity, theoptical disc 2 of a preset recording capacity may be reduced in size.The optical disc 2 may be scanned as the optical pickup 68 is located atan optional position across the inner and outer rims of the maincartridge body unit 5, the main cartridge body unit 5 and hence therecording and/or reproducing apparatus employing it may be reduced insize.

Although the disc cartridge 1 having the replay-only optical disc 2housed therein has been explained in the foregoing, the presentinvention may similarly be applied to a recording and/or reproducingoptical disc adapted for re-recording the information signals or othertypes of the recording mediums with comparable merits.

The present invention is not limited to the embodiments described abovewith reference to the drawings, such that various modifications orsubstitutions that may be apparent to those skilled in the art may beimplemented without departing from the scope of the invention as setforth and defined in the claims.

It should be understood that various changes and modifications to thepresently preferred embodiments described herein will be apparent tothose skilled in the art. Such changes and modifications can be madewithout departing from the spirit and scope of the present invention andwithout diminishing its intended advantages. It is therefore intendedthat such changes and modifications be covered by the appended claims.

1. A disc cartridge comprising a disc; and a main cartridge body unithaving said disc rotatably housed therein; one lateral surface of saidmain cartridge body unit being a substantially semicircular arcuatesection having a center of said disc housed in said main cartridge bodyunit as a center thereof, wherein a back side of said main cartridgebody unit opposite said arcuate section is a curved section having acurvature smaller than a curvature of said arcuate section wherein anengagement recess engaged by a part of an ejection unit provided to arecording and/or reproducing apparatus loaded with the disc cartridge isformed in the lateral side of the main cartridge body unit carrying saidarcuate section, and wherein a cut-out portion opened in an oppositedirection to an inserting direction is formed on a side of saidengagement recess opposite to the inserting direction into the recordingand/or reproducing apparatus.
 2. The disc cartridge according to claim1, wherein said arcuate section is formed on an inserting side of saidmain cartridge body unit into a recording and/or reproducing apparatus.3. The disc cartridge according to claim 2, wherein the curved sectionis opposite to an inserting end of said main cartridge body unit.
 4. Thedisc cartridge according to claim 1, wherein said main cartridge bodyunit includes a recording and/or reproducing aperture for exposing atleast a portion of a signal recording area of said disc to outsideacross an inner rim and an outer rim of the disc and wherein saidrecording and/or reproducing aperture is formed for being opened in alateral side of said main cartridge body unit other than the lateralside formed as said arcuate section.
 5. The disc cartridge according toclaim 4, wherein a shutter unit for opening/closing said recordingand/or reproducing aperture is movably mounted to said main cartridgebody unit.
 6. The disc cartridge according to claim 5, wherein saidshutter unit is moved along a lateral side of said main cartridge bodyunit other than said arcuate section of said main cartridge body unitfor opening closing said recording and/or reproducing aperture.
 7. Thedisc cartridge according to claim 6, wherein the lateral side alongwhich is moved said shutter unit is a side parallel to a movementdirection of said shutter unit.
 8. The disc cartridge according to claim1, wherein another engagement recess is formed in a lateral side of saidmain cartridge body unit carrying said engagement recess.
 9. The disccartridge according to claim 8, wherein a recording and/or reproducingaperture for exposing at least a portion of said disc is formed in saidmain cartridge body unit, and wherein said recording and/or reproducingaperture is formed for being opened in a lateral surface of said maincartridge body unit, formed with said engagement recess, other than thelateral side carrying said arcuate section of the main cartridge bodyunit.
 10. A disc cartridge comprising a disc; and a main cartridge bodyunit having said disc rotatably housed therein; one lateral surface ofsaid main cartridge body unit being a substantially semicircular arcuatesection having a center of said disc housed in said main cartridge bodyunit as a center thereof, wherein an engagement recess engaged by a partof an ejection unit provided to a recording and/or reproducing apparatusloaded with the disc cartridge is formed in the lateral side of the maincartridge body unit carrying said arcuate section, and wherein a cut-outportion opened in an opposite direction to an inserting direction isformed on a side of said engagement recess opposite to the insertingdirection into the recording and/or reproducing apparatus.
 11. The disccartridge according to claim 10, wherein another engagement recess isformed in a lateral side of said main cartridge body unit carrying saidengagement recess.
 12. The disc cartridge according to claim 11, whereina recording and/or reproducing aperture for exposing at least a portionof said disc is formed in said main cartridge body unit, and whereinsaid recording and/or reproducing aperture is formed for being opened ina lateral surface of said main cartridge body unit, formed with saidengagement recess, other than the lateral side carrying said arcuatesection of the main cartridge body unit.